Most likely cause

Overwatering is the top cause of a mushy Snake Plant. These are succulent-type plants built for drought; their roots need air between waterings, and when the soil stays saturated the roots are starved of oxygen, break down, and rot spreads up into the leaf bases.

You can confirm it by unpotting the plant. Rotten roots are brown, soft and slimy and slide apart in your fingers, often with a sour smell, while healthy roots are pale and firm. If the leaves are squishy at the soil line and the mix is still damp, this is the driver. Once you trim the rot and repot dry, firm new growth means it is recovering.

Other causes

These rank below overwatering but usually make it worse.

  • No drainage holes. Water collects at the bottom of the pot; the lower root ball stays permanently wet even when the surface looks dry.
  • Cold temperatures. Below 50F the plant barely drinks, so soil stays wet for weeks and tissue is damaged directly; rot follows a chilly windowsill or draft.
  • Watering on a schedule. Fixed weekly watering ignores how dry the soil actually is; the mix never gets the chance to dry out fully.
  • An oversized pot. A pot far larger than the root ball holds a reservoir of wet soil the roots cannot use up, keeping them soggy for too long.

How to fix it

  1. Unpot and inspect. Slide the plant out and brush off the soil so you can see the full root ball and the base of every leaf.
  2. Cut away all rot. With clean, sharp scissors, remove every mushy leaf at soil level and trim off all brown, slimy roots back to firm, pale tissue.
  3. Let the cuts callus. Leave the plant out of soil in a dry, shaded spot for 24 hours so the wounds dry and seal before replanting.
  4. Repot in gritty mix. Use a fast-draining cactus or succulent mix in a pot with drainage holes, sized just to the root ball, not oversized.
  5. Wait to water. Leave the freshly repotted plant dry for about a week, then water only once the soil is completely dry throughout.
  6. Keep it warm and bright. Place it in bright indirect light above 55F, away from cold drafts, to help it drink steadily and rebuild roots.
CauseTell-tale signFix
OverwateringMushy base, wet soil, slimy rootsUnpot, trim rot, repot dry
No drainageSoggy bottom, dry surfaceMove to a pot with holes
ColdWet soil for weeks, draft nearbyKeep above 55F, water less
Fixed scheduleSoil watered while still dampWater only when fully dry
Oversized potSlow-drying soil around small rootsPot down to root-ball size